In a prior surgical handpiece of the above-mentioned type, marketed by the assignee of the present invention, rotor position sensors, typically Hall sensors, are circumferentially spaced around one end portion of a permanent magnet rotor to continuously sense the circumferential location of the rotating magnetic poles of such rotor and thereby, through a suitable conventional control circuit, control polarity and amplitude of the energization of stator windings, to cause the handpiece to drive a surgical tool in the desired rotation direction and at the desired speed. Handpieces of this type incorporate high speed motors, for example in the range of 40,000 rpm to 100,000 rpm.
In this prior handpiece motor, elongate insulated wires are soldered to short trimmed conductive leads of the sensors and to stator field winding ends and are bent through a common tortuous path rearwardly to soldered connections on the front of a rear opening, cup shaped pin holder at the rear of the handpiece. Rear facing pins of the pin holder releasably engage sockets in a conventional plug insertable into the rear end of the handpiece. The plug connects through an elongate multiconductor cable to conventional control circuitry in a remote console. With three sensors and three pins per sensor, the result was nine elongate insulated sensor wires, in addition to three more field winding wires, led tortuously through the handpiece housing and 24 solder connections. Accordingly, the assembly of these parts was labor intensive and thus costly. There was risk of bad solder joints. In addition, the required length and flexibility of the tortuously led insulated connecting wires prevented these wires from themselves reliably positively locating the sensors precisely with respect to each other and the rotor. In addition, the bundle of the insulated connecting wires taken in total, was bulky and at odds with the need for compactness in a motor structure to be inserted into a comfortable handheld surgical handpiece. Further, this prior arrangement of insulated connecting wires risked pinching and breaking of individual wires and loosening of solder joints during assembly into the handpiece housing, requiring subsequent repair. Accordingly, the objects and purposes of the present invention include provision of a surgical handpiece of the type aforementioned, but having improved physical mounting and electrical connection structure for the sensors and which avoids the difficulties in the prior structure above-discussed.
Other objects and purposes of the invention will be apparent to those acquainted with the apparatus of this general kind upon reading the accompanying description and inspecting the accompanying drawings.